1. Field of the Invention
The present invention pertains generally to the cutting of glass patterns from a blank sheet of glass, and more particularly to simultaneously cutting a plurality of such patterns from the blank sheet by means of abrasive fluid jets and separating the pattern cuts from the resulting selvedge material.
2. Description of the Prior Art
There is a trend in automotive vehicle styling to employ glazing units having irregular outlines and/or interior cut out areas or openings for various purposes. One such glazing unit particularly in demand comprises a generally triangular light having a similarly shaped triangular opening in one of its corner regions. The units may have rounded corners. Formation of such units and removal of the interior portion by conventional glass cutting techniques is difficult, time consuming and expensive. Thus, automotive glass is normally cut to the prescribed pattern by scoring one surface, and then flexing the glass along the score line to break out the pattern. This technique is not entirely satisfactory for severing glass along curved lines or for removing interior portions from a glass sheet.
The use of high pressure abrasive fluid jets has been proposed for cutting intricate patterns from glass and for producing interior cut outs within glass blanks. U.S. Pat. Nos. 4,656,791 and 4,703,591 pertain to such abrasive jet cutting of glass and are concerned, respectively, with support mechanism for the glass blank during cutting and for increasing the cutting speed while maintaining the quality of the cut edge. While the disclosed inventions represent a significant advance in the art of cutting patterns from glass they have certain limitations due to the time required for producing each pattern cut unit. They may thus not be able to produce the units in the volume desired for an automotive glass fabrication line.
U.S. Pat. No. 3,859,878 to Bonaddio et al. suggests the use of ganged scoring tools in order to simultaneously subdivide a glass sheet into a plurality of small pieces using conventional scoring and flexing techniques. While the device increases the rate at which large sheets may be subdivided along generally straight lines, it is not adapted to cutting intricate patterns or to making interior cutouts in the sheets. U.S. Pat. No. 4,278,193 to Perelman et al. likewise is concerned with conventional scoring and breaking techniques. First and second score lines are applied to a glass sheet so as to define two nested glass blanks to be subsequently broken out from the glass. The glass is split between the blanks into two parts. The parts are then separated and the blanks are broken out from each part.
U.S. Pat. No. 4,362,461 to Cathers pertains to a system for scoring, snapping, separating and stacking sheets employing a vacuum device for lifting or picking up selected ones of sheet articles as from a conveyor and laterally transferring and depositing them in another area. The wall of the vacuum chamber facing the sheet articles has an apertured plate covered by a foraminous pad which defines the sheet engaging surface. An isolating device provided within the vacuum chamber moves between a first position where it isolates the chamber from the vacuum source and a second position where it provides communication with the source for supplying vacuum to appropriate areas of the plate and pad for picking up the selected one of the sheets.
U.S. Pat. No. 4,467,168 to Morgan et al. discloses use of a laser for cutting glass to intricate shapes. The glass is suitably supported along either side of the proposed line of cut. A laser beam directed onto the glass vaporizes a first thickness of the glass, and a jet of gas directed to the laser focal point removes the vaporized glass and penetrates the glass. The laser and glass are moved relative to one another to sever the glass along the desired path.